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Microsoft Exchange Online outage affecting global users

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Last updated
1 unique sources, 2 articles

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Microsoft confirmed an outage affecting Exchange Online users worldwide, causing access issues to emails and calendars. The incident began early in the morning and persisted for over 16 hours. The root cause involved a specific software build version that led to repeated database dismounts and failovers, resulting in increased CPU utilization and message queue buildup. The outage was mitigated after implementing a configuration change and restoring degraded infrastructure. The issue was initially believed to be region-specific but later confirmed to affect users globally. Microsoft identified a recurring issue with a specific software build version causing repeated database dismounts and failovers, leading to increased CPU utilization and message queue buildup. The company has since mitigated the outage and is monitoring the environment to ensure stability. A new outage tracked under incident EX1189820 is preventing customers from accessing their mailboxes using the classic Outlook desktop client. The impact is specific to users in the Asia Pacific and North America regions. Microsoft advises affected customers to use Outlook on the Web as a workaround. Additionally, a separate incident (EX1189768) is causing search issues for classic Outlook users.

Timeline

  1. 25.11.2025 18:18 1 articles · 23h ago

    New Exchange Online outage blocks access to Outlook mailboxes

    Microsoft is investigating an Exchange Online service outage preventing customers from accessing their mailboxes using the classic Outlook desktop client. The outage, tracked under incident EX1189820, is causing server connection and login issues. The impact is specific to users in the Asia Pacific and North America regions. Microsoft advises affected customers to use Outlook on the Web as a workaround. Additionally, a separate incident (EX1189768) is causing search issues for classic Outlook users.

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  2. 11.09.2025 22:43 2 articles · 2mo ago

    Microsoft mitigates Exchange Online outage affecting global users

    Microsoft identified and mitigated an outage affecting Exchange Online users worldwide. The outage began early in the morning and persisted for over 16 hours, causing access issues to emails and calendars. The root cause involved a specific software build version that led to repeated database dismounts and failovers, resulting in increased CPU utilization and message queue buildup. The issue was mitigated after implementing a configuration change and restoring degraded infrastructure. Microsoft is monitoring the environment to ensure stability.

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Information Snippets

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